1. Field of the Invention
The invention relates to a method and a hemostatic patch for local and spontaneous hemostasis for treating bleeding wounds that are the result of injuries or surgery.
2. Description of the Related Art
It is known to use patches or compresses etc. made of cellulose, gelatin, or collagen for effecting hemostasis of bleeding wounds, caused by injury or by surgical intervention. Also known is the application of fibrin adhesives or thrombin.
In the case of neurosurgical and microsurgical operations, it is customary to employ sponges or compresses which are impregnated or soaked with physiological saline solutions for effecting hemostasis. Trying to effect hemostasis in this way is usually time-consuming and requires a large number of sponges or compresses.
The use of medical sponges or compresses is moreover limited because hemostasis can be effected only over a limited period of time.
International patent document WO 93/24086 describes a sponge whose adsorbent textile part is comprised of several layers of textile material and has an x-ray-opaque string. Because of the multi-layer configuration of the textile part the sponge is relatively thick and is therefore not suitable for neurosurgical and microsurgical operations.
Hemostasis refers to the action of stopping the bleeding of a wound and is the result of interaction of various functions: vasocontraction as well as vasoretraction, aggregation of platelets, as well as blood coagulation or clotting. These various functions can be assisted by administering substances which directly or indirectly affect hemostasis, such as vitamin K, astringent agents, thrombin, high-molecular colloids, fibrin foam as well as blood transfusions, substitution of coagulation factors as well as local cooling or the like.
Blood coagulation is a very complex process which takes place in several stages. The end result is the formation of insoluble fibrin from the fibrinogen which is contained in the blood plasma. This process of fibrin formation is catalyzed by thrombin in interaction with calcium ions. Approximately 30 different factors interact to accomplish blood coagulation, inter alia, the coagulation factors of the blood plasma and numerous platelet factors.
Hemostasis occurs in two stages: primary hemostasis and secondary hemostasis. In the initial stage, which is generally referred to as primary hemostasis, accumulation and aggregation of platelets occur and the resulting “plug” initially closes the wound to slow down the loss of blood. The accumulation of the platelets and their aggregation are controlled primarily by thromboxane A2. The initial closure of the wound is also assisted by so-called vasoconstricting substances, for example, serotonin, which provide a reduction of the opening of the wound. The aggregation or fusion of the platelets results in the release of the so-called platelet factor 3 which plays an important role in the second stage of hemostasis (secondary hemostasis)—the blood coagulation. The process of secondary hemostasis encompasses the sequential activation of plasma coagulation factors leading within five to seven minutes to the formation of a mechanically stable fibrin thrombus around the initial platelet plug.
Another approach to suppress bleeding is the use of antifibrinolytic agents, i.e., agents that act to prevent dissolution of fibrin clots. As is known in the medical field, such substances are administered in the form of a solution to be injected or in the form of tablets or pills to be administered orally in the case of hyperfibrinolysis, i.e., increased fibrinolysis as a result of increased levels of plasminogen. They are used to treat serious bleeding, for example, after dental surgery (particularly in patients with hemophilia) or other kinds of surgery and are also given before an operation to prevent serious bleeding in patients. The maximum effect of the application of an antifibrinolytic agent, for example, by means of injection, is reached after about six hours. Side effects such as nausea, vomiting, or diarrhea are observed; these side effects will subside when the concentration of the substance in the blood decreases.